09 January, 2022

Magical speaker cables - part 2

Cable with large distance between the
conductors (Schnerzinger)
Part 1 of this article concluded that it is important to have thick enough cables in order to bring down the resistance. It also showed two examples of slightly more exotic cables, shown in the first two images here.

The first example had a large distance between the conductors and was placed on its own stand to get distance from the floor. It was designed to minimize capacitance between conductors. Another design criterion was to minimize the impact of vibrations created by the speakers themselves.

Twisted multi-conductor cable
The next example was a cable made by twisting together many thinner conductors, in this case a do-it-yourself cable. It was designed to have the least possible inductance and also to minimize the skin effect.

There is no shortage of science-based claims for how cables affect sound. There are so many of them that this blog post, where my ambition is to say something about all of them, gets to be a little longer than I would have liked it to be. If you are impatient, you may go to the end and just see the conclusion. For the curious, I will consider the claims one by one.

02 January, 2022

Magical speaker cables - part 1

Pear Anjou speaker cable
I’m sure many have seen advertisements for speaker cables costing thousands of dollars. Some take this very seriously while others consider it to be pseudoscience. 

What should one believe? Here I want to help clarify the concepts.

A climax in the cable dispute may have been reached in 2007 when the skeptic James Randi offered a reward of 1 million dollars if anyone could prove that speaker cables costing $2750 for a pair of 1 meter long cables provided any improvements. He was provoked by the claims of the Pear Anjou cables shown in the image.

26 October, 2021

Updated Arduino Multi Face GPS Clock

The GPSClock from last month has now been updated and software version 1.10 1.1.0 is available on Github. The main upgrade is the possibility to use a rotary encoder for selecting display screen or clock face.

In addition a new screen showing Easter for the next three years, according to both the Gregorian (Western) and Julian (Eastern) calendars, has been added as number 22. The dates are shown in the Gregorian calendar:

A new screen showing the clock in binary, octal, decimal, and hex format is screen 21:

29 September, 2021

Multi Face GPS Clock published

Version 1 of my Multi Face GPS Clock is here, as open source software for the Arduino Mega. It has some 22 19 different display screens showing time, location, solar and lunar positions and rise/set times. It shows UTC time as received from the GPS satellites and local time where it automatically adjust for summer time. The initial screen, no. 0, is this:

23 August, 2021

Finally figured out the moon

I’ve been working on a GPS-controlled Arduino clock for some years and had set myself the goal of showing time for moonrise and for moonset for the present day. That turned out to be much harder than I had thought.

Finally, over the last few weeks I managed to adapt lunarCycle.c to Arduino and get it to work as shown in the display here. My ambition is now eventually to publish this project on GitHub as I’ve had several requests for it.

The display here shows local time and date, moon phase on line 2, present moon elevation and moon azimuth on line 3, and the next rise time of the moon and at which position on the final line. Follow label ‘Arduino clock’ below for more posts about this clock.

10 July, 2021

Coordinated WSPR band hopping with the QRPLabs U3S

There is a recommended sequence for multi-band transmission on WSPR. It is given in the K1JT WSPR documentation. If enough receivers follow this sequence, then presumably letting WSPR transmissions also follow it, will increase the chance of detection. 

The recommended band hopping sequence cycles through 10 bands over a 20 minute period according to this table:

Band (m)   160  80  60  40  30  20  17  15  12  10
UTC Minute  00  02  04  06  08  10  12  14  16  18
            20  22  24  26  28  30  32  34  36  38
            40  42  44  46  48  50  52  54  56  58

The multi-band U3S is capable of adhering to such a sequence. There are however three considerations that need to be taken into account. 

14 April, 2021

Learning the hard way that plastic TO-92 is affected by humidity

I've had my APRS temperature station running since 2012. It is based on a DS18S20 sensor that just sticks out of a window. However, after some time it started to give too high readings, and after having replaced it several times I found out that I needed to waterproof it better. It seems that the TO-92 plastic housing, shown here to the right, somehow was influenced by humidity.

I wasn't able to find waterproofed DS18S20 sensors, but I could find ones with DS18B20. I got one and connected it, but it only showed -1 C regardless of weather. The software in the Opentracker USB was not able to read it, although I have Arduino programs that can read both.

07 April, 2021

Now active via the International Space Station

I happened to set my 2m receiver to the APRS (Automatic Packet Reporting System) frequency of the International Space Station (ISS), 145.825 MHz, and lo and behold stations in Central and Southern Europe started to appear. This is not rocket science, but for me it's a first. (Well actually the ISS is a kind of rocket ...)

Here in Oslo, using the local APRS service, I can also receive Swedish and Danish stations when conditions are good, but never Spain, Italy, Greece, Romania, Ukraine, Russia or Turkey. When a message appeared from NA1SS itself, the station onboard the ISS, I felt that I had really nailed it (see image). But ISS had more in store for me.